Finding gain percent from selling price and profit amount An article is sold for Rs 100 with a gain of Rs 10. What is the gain percentage?

Introduction / Context:
Gain percent is computed on cost price, not on selling price. When you know the selling price and the absolute profit, first derive the cost price, then compute the percentage gain relative to cost.

Given Data / Assumptions:

• Selling price (SP) = Rs 100.
• Profit (gain) = Rs 10.
• Find gain % on cost price (CP).

Concept / Approach:
Profit = SP - CP. Gain % = (Profit / CP) * 100. Use the given numbers to find CP and then the percentage.

Step-by-Step Solution:
Profit = 10, SP = 100 ⇒ CP = SP - Profit = 100 - 10 = 90.Gain % = (10 / 90) * 100 = 11.111... %.As a mixed fraction, 11 1/9%.

Verification / Alternative check:
If CP = 90 and gain is 11 1/9%, then SP = 90 × (1 + 1/9) = 90 × (10/9) = 100 (matches data).

Why Other Options Are Wrong:
9% and 10% use the wrong base; 12 1/2% overshoots. 'None of these' is incorrect because 11 1/9% is exact.

Common Pitfalls:
Computing gain % on SP instead of CP, or rounding 11.11% to 10% incorrectly.

Final Answer:
11 1/9%